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HELMINTH OVA AND VIRUS DETECTION IN BIOSOLIDS
The objectives of this task are to:
Sewage sludge (also known as biosolids), a byproduct from domestic sewage treatment, is often used as an organic soil conditioner and fertilizer. Raw sludge must be treated to reduce levels of potential human pathogenic agents before being used for this purpose. The domestic use of treated sludge is regulated by the Subpart D requirements of 40 CFR Part 503. This regulation was promulgated in 1993 under the authority of the Clean Water Act. It specifies two classes of treated sludge. The goal of the treatment processes required to produce class A material is to reduce pathogens to below detectable levels. Class B sludge has reduced levels of pathogens, but uses site and time restrictions to reduce exposure to the public.
In response to a requirement of the Clean Water Act to review sludge regulations, EPA asked the National Research Council (NRC) to examine the technical basis for chemical and microbial risk reductions underlying the sludge rule. The NRC committee concluded that "there is no documented scientific evidence to indicate that the Part 503 rule has failed to protect human health," but recommended additional research to strengthen risk assessment. Their report specifically identifies the need to standardize and validate methods for detection and enumeration of specific pathogens. EPA has responded to their recommendation by proposing to validate methods for fecal coliform and Salmonella bacteria and to develop improved methods for viruses and Helminth ova. A major purpose of this task is to provide EPA with improved methods for the latter two groups of pathogens. These methods will provide the Agency with enhanced methods to evaluate the pathogen removal effectiveness of new sludge treatment processes. A second purpose of this task is to conduct an exposure measurement workshop on pathogens in sewage sludge.